Automatic diverter for sugar contaminated condensates



y 1945. A. M. HEWLETT 2,376,694

AUTOMATIC DIVERTER FOR SUGAR CONTAMINATED CONDENSATES Filed Oct. 3, 1942Ian UM RJR I BFILER compzuuo V'ENT 1'0 20 CONDENSATE FROM H JUICE HEATERTO WASTE I lNVENTOR Allen Mjz'ewlefi BY 4.4 M

ATTORNEYS Patented May 22, 1945 l AUTOMATIC DIVEBTER FOB SUGARCONTAMINATED CONDENSATES Allen M. Hewlett,

new, names, Territory o H wall Application October a, 1942, Serial No.access 6 Claims. (01. 131-438) In the manufacture of sugar from cane orbeet juice. it is common practice to utilize the vapor from one or morestages of the evaporators to to the clarifier or settling tanks. Thisresults in the condensation of the vapors and permits the condensate tobe used as extra distilled ieed water for the boilers. It is also commonin sugar mills to utilize the condensate from the second and/orsucceeding stages 01' the evaporators for the boiler reed. By condensateis meant water produced by the change of state resulting when watervapor gives up, its heat of vaporization, and superheat ii' any, tomediums in heat transfer relationship therewith, such mediums beingusually the heat transfer surfaces of evaporator calandrias, heaters andsurface condensers.- Dangers are inherent in the use 01' such condensatein the bo"ilers if. it contains any sugar such as might result fromleakage in the juice heater, entrainment in the vapor from theevaporators or other causeswh'ereby sugar juicegets into the condensate.

This has been a problem oi considerable importance in raw sugar millsbecause of the very nature of sugar. Most organic or mineralimpuritiesin boiler feed waters are. undesirable, but are not particularly harmfulexcept over a considerable period of time or in boilers operating athigh pressures and ratings. Sugar, however, is almost as dangerous asall even in boilers that operate at the low ratings and the lowpressures common to sugar mills.

Neither pure water nor a pure solution of sugar is an electrolyte, andtherefore'the presence of sugar in the condensate cannot be directlydetected by electrolytic means. Furthermore, the pe of direct electriccurrent through the solution is objectionable, because of the eii'ect ofelectrolytic polarization.

'Iunderstand that all previous efforts to detect heat the juice afterliming'and before delivery percentage of the condensate, and theseelectrolytic impurities be a far smaller percentage, I have discoveredhow the presence of the sugar in the condensate may be detected throughthe presence of these impurities which accompany the sugar.

In carrying out my invention, I provide means whereby an alternatingcurrent of relatively high voltage may pass between spaced electrodes inthe condensate when such condensate contains even a relatively smallamount of sugar with its accompanying much smaller amount of mineralsalts and other impurities. The current being alternating instead ofdirect, nullifies the effect of electrolytic polarization, and the highvoltage permits the passage of suflicient current to operate anindicator and/or control mechanism even when there are mere tracesof theelectrolytic impurities present. By the term high voltage a1- ternatingcurrent I mean voltages in the region of 100 volts or more andfrequencies such as 60 4 a relay or the like to veifect actuation ofsuitable valves by whichthe condensate is diverted and the presence ofsugar in condensate by electrical.

means have ended in failure.

I have discovered a method whereby the presence of sugar in thecondensate can be detected in a simple and practical manner, and suchcondensate as contains sugar may be diverted and prevented from enteringor from returning to the feed water supply.

The juice in the heater as well as the concentrate in the evaporatorscontains arelatively low but relatively fixed percentage of impuritiessuch as mineral salts or inorganic acids which are electrolytes, and,even though such Juice as may leak into the condensate or be entrainedin the vapors from the evaporators may be a very small vapors andnon-condensable gases. v

temperature or the incoming condensate is not prevented from going tothe feed water supply, and to effect actuation of a signal or alarm,just so'long as the condensate is beingcontaminated. The valve may bereversed and the signal or alarm stopped or started automatically whenthe contamination ceases. 7

Various other objects; features and advantages of the invention'will beapparent from the following particular description, and from aninspection of the accompanying drawing, diagrammatically showing a formof apparatus which embodies the present invention and which can beemployed to carry out the process of the present invention.

In carrying out my improved process, the vapor from the evaporatorcondensed in the juice heater is delivered as a condensate through pipeIt and may accumulate in a closed receiving tank ii, provided with avent I2 for the escape of flash much below 212 R, most of the oxy n andsin-,- monia in the system flash oil in the space at the top of the tankII, and escape to the atmosphere through the vent II. An outlet I3 inthe bottom of the tank Ii controlled by a valve I4 I serves as a meansby which the contents of the tank ll may be'dumped to waste or divertedf any desired purpose.

Since the densate before delivery to the boiler, without affecting the'electrolytic condition of the liquid in themaintankll.Ifitisdesiredtomodifythe character of this portion of the boiler feedwater, there may be provided a drum or vessel It containing boilercompound solution and having a valved discharge pipe 23 directly overthe open top of the auxiliary tank It whereby chemicals,

may be introduced into the condensate in said tank.Theliquidintheauxiliarytank llismaintained at constant level byan-overflow pipe 23 leading to a hotwell. A valved branch. pipe 24connected to the overflow pipe 23 facilitates col-. 2o

' open, so'long as the conductivity of the conlection of check samples,and may also serve'asa means by which the overflow may be drained to Fordetermining thepresence of sugar in the condensate. there is provided apair of normally fixed but relatively movable electrodes 25 and 26,connected in the circuit of a current supply line 21. and made ofsuitable electrode material such as brass; 0ne-of these electrodes 2I.isshown as being fixed in an insulating sleeve 3li extend- 3o electrodeand is movable endwise towards or away from the exposed end of thelatter. Merely as 'an example of the many ways in which the electrode 2Qmay be mounted, it is shown as-either connected to or forming a part ofa handled member insulated from the tank II and threaded in a bonnet or(bracket 3| connected to the outside of the tank.

The electrodes 2l'and 23-are connected to opposite mains of a highvoltage alternating current line 21 such as one of 110 volt cycles, asillustrated. One supply line 21a is connected to the electrode 25, whilethe other line 21b is electrically connected to the other electrode 20through the coil of a small solenoid a in series with said 5 electrode23. A small signal light 23 is connectedin series with the electrodes"and 23, andin parallel with the solenoid 32, so that it slows dimly.when the main switch 21c is closed, but becomes brighter as theconductivity of the solution in 55 tank ll increases. When the solenoid32 finally becomes sufliciently energized to pull up its plunger, thesignal light 23' glows very brightLv.

The solenoid 32 acts to control a branch circult in which there is amotor for operating the waste valve is at the bottom r the tank u.

This motor may be of any. suitable-type and may activate the valve [4 byany suitable operating mechanism. Merely as an example, this is shown asa. powerful volt solenoid" having its a plunger to the waste valve. by athruster rod 34. This solenoid 33 is mounted in a secondarycircuitscross the supply lines- 2'lin parallel with the electrodes 2'and 2' and provided with a suitable switch ll actuated by the solenoid32 so that the circuit of the valve actuating solenoid 83 is closed whenthe conductivity of the liquid in the tank-ll exceeds apredeterminodvalue. This switch 3| isshown as an ex-' 7 tube has itscontacts open when the tube is horizontal and closed when the tube istilted.

As will be apparent, the electrodes 2! and 23 are completely immersed inthe hot condensate and adjustment may be-made by screwing the electrode28 slowlylnwardly until a point is reached at which the resistance ofthe primary circuit of the solenoid 32 is sufllciently low to permitpassage of a current of suchmagnitude that the plunger of said solenoidbegins to lift slightly. Then the electrode is retracted just enough toallow the plunger of the solenoid 32 to'return to rest. The condensateis then tested chemically for traces of sugar. If no trace or onlyslight traces are found, the setting will be considered satisfactory.The electrodes 25 and 23 should desirably beseparated by aboutone-eighth of an inch or less when set as described. With this settingof the electrodes, the parts will remain as shown and the secondarycircuit 'will remain densate does not exceed a predetermined valuedetermined'by said setting and said condensate is substantially free ofsugar. 7

Immediately upon contamination with cane or beet juice or concentratefrom leakage, entrainment or other causes, the electrolytic impuritiesin said juice or concentrate increase the conductivity of the liquidbetween the two electrodes 2! and26, thereby permitting more current topass through the coil of the solenoid 32.v When,this

conductivity reaches a certain degree, the 'solenoid 32 will beenergized sumciently to tilt the switch 35 into circuit closingposition, thereby energizing the valve actuating solenoid 33. Thiscauses the opening of the valve M at the bottom 61 the tank I I, and.the resultant dumping of the contaminated condensate to waste. .Theincreased conductivity across the electrodes 2! and 28 will also causesignal light 23 to glow more brightly.

As soon as the level of liquid in the tank gets below the' shoulder ofthe insulating sleeve 33 on the'fixed electrode 25, all clncults areopened and the dump valve I4 closed. The receiving tank ll may thenrefill, if the contamination has ceased, but if the refilling condensateis still contamihated, the above series of events are repeated, untilthe condensate delivered to the tank is substantially free of sugar. Inthe event of a tube leak, the process will be repeated'until theresultant flashing of the pilot light is noticed by the operator. Theoperator can then by-pass the entire system until the leak has beenrepaired More precise settings of the electrodes in the condensate may,if desired, be determined by theuse of an A. C. Wheatstone bridge and agalva nometer witha properly graduated dial.

Also, the solenoid 33 constitutes only one'form of motor and the dumpvalve It may be of any suitable type. Such a motor, for instance, mayconstitute part of a G. E. Thruster device controlled-from the switch35. I

In addition to the signal lamp 23, a remotely located lamp 38 ofsuitable voltage may be connected across the mains 21 toindicate failureof 3 power or the blowing of-the fuses. Also, in'lddltion to the signal;lamp 28 'or in place thereof, a remotely located lamp 31 of-suitablevoltage may be connected in parallelwith the solenoid 33 to indicatedumping operations. 7

As many changes can be mad in the above method and apparatus, and manyapparently widely diflerent embodiments of this invention ample of themercoid type, in which a mercury 15 can be made'without departing fromthe scope of the claims, it is intended that all matter astained in theabove description or shown in the. accompanying drawing shall beinterpreted aslet, an outlet for the outflow of condensate from thetank, means for maintaining a normal substantially constant liquid levelin said tank, a normally closed dump valve at the bottom of said tankfor condensate contaminated with sugar, a source of alternating current,a pair of spaced electrodes in said tank below said predetermined level,and means for opening said dump valve when the condensate becomesconductive due to impurities accompanying the sugar contam inating saidcondensate, and by current flow between said electrodes from saidsource, said valve being constructed and arranged to automatically closewhen the liquid level in the tank gets below one of said electrodes.

i 2. An apparatus forcontrolling the flow of condensate from thecondensers of sugar evaporators, including a tank having a pair ofelectrodes, a permanentlyopen outlet for uncontaminated condensate,means associated with said outlet for maintaining a substantiallyconstant liquid level in said tank above said electrodes, an outlettromsaid tank below said level, a normally closedvalve for controllingsaid second mentioned outlet, and operating means for opening said valvewhen the condensate between said electrodes is conductive due toimpurities accom panying thesugar contaminating said condensate, andcurrent may flow between said electrodes, said operatin means beingconstructed 4, An apparatus or the character described, including a tankhaving an inlet and an outlet for the continuous flow therethrough-of'condensate from the evaporators of a sugar mill, said outlet being sopositioned as to maintain a substantially constant liquid level in saidapparatus, said tank having a second outlet below said first mentionedoutlet, a valvefor said second outlet and normally held closed by theaction of gravity, 3

high voltage alternating current circuit having a pair of spacedelectrodes extending into the condensate in said tank, anelectro-magnetic device in saidcircuit and operable when the electricalconductivity of the condensate between said electrodes exceeds apredetermined value, and means operable when said electro-ma neticdevice is operated for opening said valve against the action of gravityand holding it open until the liquid level in said tank drops below atleast one of said electrodes.

5. an apparatus for controlling the flow oi condensate from anevaporator for sugar solutions to ,the source of feed water for aboiler, which includes a tank having a condensate inlet. an outlet forthe outflow of condensate from the tank, so positioned. that thecondensate will flow and arranged so as to close said valve when saidcurrent flow ceases. I

3. An apparatus for controlling the flow of condensate from thecondensers of sugar evaporators. including a tank having a pair ofelectrodes, a permanently open outlet for uncontaminated condensate,means associated with said outlet for maintaining a substantiallyconstant liquid level in said tank above said electrodes, an outlet fromsaid tank below said level, a valve normally biased to closed sition forcontrolling said second mentioned outlet, and operating means foropening said valve when the condensate between said electrodes isconductive due to impurities accompanying the sugar contaminatingsaldcondensate and holding it open only until the liquid level in saidtank gets below one of said electrodes. I

therefromonly when the liquid level is above a? predetermined level, anormally closed dump valve at the bottom of said tank for condensatecontaminated with sugar, a source of alternating current, a pair ofspaced electrodes in said tank below said predetermined level, and meansfor opening said dump valve when the condensate becomes conductive dueto impurities accompanying the sugar contaminating said condensate andby current flow between said electrodes from said source, said valvebeing so constructed as to automatically close when the liquid level inthe tank gets below one of said electrodes.

6. An apparatus for controlling the flow of condensate from anevaporator for sugar solutions to the source of feed water for a boiler.

which includes a tank having an inlet and an outlet for the normalcontinuous flow of con densate through the tank to said source of feedwater, means for maintaining a normal substantially constant liquidlevel during .said continuous flow, an alternating electric currentcircuit including a pairof electrodes in said tank below said normalliquid level, a second outlet at the bottom of said tank, a valvenormally closing said second outlet, and means actuated by the flow oicurrent between said electrodes when said condensate becomescontaminated by sugar and is thereby rendered conductive by sugar, foropening'said valve, said fialve being constructed to close when flow ofcurrent is terminated.

AILEN M. HEWLETT,

impurities in the- 4

